1. Field of the Invention
The subject invention is directed to a stamp formed connector for joining three or more conventional pipes. The stamp formed connector enables alignment of pipes that could not readily be achieved with conventional pipe joining techniques, and enables a pipe routing to obtain equal lengths for the exhaust pipes.
2. Description of the Prior Art
Exhaust systems extend from the engine of the vehicle to a location where exhaust gases can be safely emitted. Most exhaust systems include at least one catalytic converter for converting certain objectionable pollutants into a less objectionable form. Exhaust systems also include at least one muffler to attenuate noise associated with the flowing exhaust gas.
Noise produced by an internal combustion engine is actually a sequential series of noise patterns corresponding respectively to the sequential controlled explosions taking place in the cylinders of the internal combustion engine. Engineers examine the loudness and frequency of noise resulting from these explosions and design an appropriate array of tubes and chambers in a muffler for attenuating the observed noise. The task of the engineer is made much more difficult if the noise from the respective explosions does not define a uniform repetitive pattern approaching the muffler. A non-uniform pattern may cause some waves to overlap with and add to others. Thus frequency and amplitude may be difficult to predict.
The exhaust system routing is selected to ensure sufficient clearance from components that are susceptible to damage from the heat generated by the exhaust system. The exhaust system routing also must provide a location that can safely accommodate the catalytic converter and another location that is sufficiently large to accept the exhaust muffler. Engineers evaluate these space limitations and analyze the noise generated by the muffler to design an appropriate exhaust system.
Exhaust system routing is more likely to be a problem for V-engines, such as V-8's or V-6's. Half the cylinders of a V-engine extend in a first plane, while the other cylinders extend in a second plane angularly aligned to the first plane. Thus, a V-engine includes two separate exhaust manifolds with separate exhaust pipes extending from the manifolds. Some vehicles with V-engines include entirely separate exhaust systems, with separate catalytic converters, separate mufflers and separate tail pipes. However, these entirely separate exhaust systems are costly and can complicate the problems of routing the system and identifying appropriate spaces for accommodating the catalytic converters and mufflers. Hence, most vehicles with V-engines have the respective pipes meet at a location upstream from the catalytic converter, such that exhaust gas streams from each of the two manifolds on the V-engine communicate with a single catalytic converter and a single muffler.
The typical prior art exhaust system having two exhaust pipes extending respectively from two manifolds requires a complex mitered joint where two pipes leading from the manifolds and one pipe leading to the catalytic converter are precisely cut at a selected angle to interfit with one another. The mitered pipes are aligned to one another to define a generally Y-shape and are welded securely together. The complex mitering and welding to make a Y-pipe connection is a time consuming procedure that is not well suited to a high degree of automation. Recent prior art for exhaust systems with two manifolds uses stamped components to avoid mitering. For example, U.S. Pat. No. 5,134,852 shows a pair of opposed stamped components are formed to define a first inlet, an outlet linearly aligned to the first inlet and a second inlet aligned to both the first inlet and the outlet.
The use of a V-engine with two exhaust pipes communicating with a single catalytic converter and a single muffler can complicate the acoustical tuning for an engine. In particular, physical constraints in the engine compartment and on the underside of the vehicle seldom permit a perfectly symmetrical exhaust system for a V-engine. As a result, the exhaust pipe leading from one manifold of a V-engine may be substantially longer than the exhaust pipe leading from the other manifold of the V-engine. These different lengths may result in different times for noise pulses to travel from the engine to the muffler, depending upon the side of the engine at which the pulses originate. The different travel times will result in a non-uniform pattern of noise pulses being delivered to the muffler. Thus, certain pulses may overlap with one another to create complex sound wave patterns that are more difficult to identify and attenuate.
Vehicles with transversely mounted V-engines are even more of a problem. A transversely mounted V-engine typically has one exhaust pipe that can travel fairly directly to the catalytic converter, and another exhaust pipe that must wrap substantially entirely around the engine. The stamp formed connector shown in U.S. Pat. No. 5,134,852 with the linearly aligned inlet and outlet does not solve the problems associated with an irregular pattern of pulses approaching the muffler.
In theory, pipes could be made with complex small radius bends in or near the engine compartment to facilitate exhaust system placement and alignment under the vehicle. However, small radius bends are difficult to make in view of excessive metal stretching involved. Similarly, bending equipment constraints often prevent successive bends from being immediately adjacent one another.
In view of the above, it is an object of the subject invention to provide an exhaust system that can more readily attenuate noise from a V-engine.
Another object of the subject invention is to provide an exhaust system for a V-engine having a uniform pattern of pulses approaching the muffler of the system.
A further object of the subject invention is to provide a connector for use with V-engines to facilitate complex pipe alignments and achieving more predictable noise patterns.